The present invention generally relates to a plasma display panel (PDP) for displaying characters or images through utilization of gas discharge and more particularly, to a plasma display device which includes a means for efficiently dissipating heat produced by the plasma display panel, and its manufacturing method.
Recently, plasma display devices acting as flat, thin and light display units having large screens are used for information terminals such as portable computers and their applicable field is expanding due to their clear display and their wide angle of field of view. In a plasma display device, a plasma display panel is formed by front and rear glass plates bonded to each other, and gas for electrical discharge is contained in a minute gap between the glass plates. Ultraviolet rays produced by electrical discharge in the gas are irradiated to phosphor on the rear glass plate such that display of light emission from the phosphor is performed. Hence, the plasma display device as a whole reaches rather high temperature through repetition of electrical discharge in the gas.
In a plasma display device, as display luminance of a plasma display panel is raised further, more heat is produced by the plasma display panel, so that the temperature of the plasma display panel rises and thus, display performance of the plasma display panel deteriorates. To actuate the plasma display panel for a long time will result in, for example, a drop in reliability of a driver circuit for driving the plasma display panel and therefore, is not preferable for performance and properties of the plasma display panel. Meanwhile, if a state in which a large difference in temperature exists in a plane of the plasma display panel continues for a long time, glass forming the plasma display panel is distorted, thereby resulting in fracture of the glass.
Therefore, in order to lower the temperature of the plasma display panel in operation and lessen distortion of the glass leading to its fracture, difference in temperature in the plane of the plasma display panel should be reduced and performance and quality of the plasma display device should be upgraded. As one of such countermeasures in a known plasma display device, a pair of draft fans 92 are provided on a rear face of a plasma display panel 91 through spacers 93 as shown in FIG. 1 and blow wind to the plasma display panel 91 as shown by the arrow A in FIG. 2 so as to lower temperature of the plasma display panel 91.
In case the plasma display panel 91 is installed in parallel with a vertical plane, temperature is distributed in a plane of the plasma display panel 91 as shown in FIG. 3 by natural convection of heat and thus, temperature difference between a high-temperature portion and a low-temperature portion reaches 10 plus several .degree.C. Meanwhile, temperature difference in the plane of the plasma display panel 91 increases according to a pattern of an image displayed on the plasma display panel 91. For example, if a state in which a small bright image (bright display) is present in a dark background (dark display) as shown in FIG. 4 continues for a long time, temperature difference between the bright image and the dark background increases considerably, so that glass forming the plasma display panel 91 is distorted, thus resulting in fracture of the plasma display panel 91. Especially, if temperature difference in the plane of the plasma display panel 91 reaches 20.degree. C. or more, there is a great risk of fracture of the plasma display panel 91.
In the conventional plasma display device provided with the draft fans 92, temperature of the plasma display panel 91 can be lowered but such a problem arises that it is difficult to reduce temperature difference in the plane of the plasma display panel 91. Furthermore, the prior art plasma display device has such drawbacks that noise of motors for the draft fans 92 is annoying, electric power is required to be supplied for driving the motors for the draft fans 92, the plasma display device as a whole becomes large due to the need for providing space for mounting the motors for the draft fans 92 and dust sucked together with external air into a casing of the plasma display device by the draft fans 92 stains the interior of the casing.
Meanwhile, in a known plasma display device, in order to lower the temperature of a plasma display panel in operation and upgrade performance and quality of the plasma display device as a whole, it is effective to attach a chassis member to a rear face of the plasma display panel. In this case, it is important that the plasma display panel and the chassis member are brought into close contact with each other.